Seminar

Globular clusters (GCs), one of the oldest structures of the universe, contain old populations of stars and stellar remnants within a small volume. These clusters are over-abundant in compact binaries: those containing a white dwarf (WD), neutron star (NS), or black hole (BH). While the existence of some of these classes of objects was known for a long time, the presence of stellar mass BHs in the GCs has only been revealed in the last decade. Owing to the fact that BH-BH mergers are common in the local universe, as unveiled via the detection of gravitational waves from binary BH mergers, there are broad scientific implications of the presence of stellar-mass BHs in GCs. Through our MAVERIC survey, we have acquired deep radio continuum images of fifty Milky Way GCs. To identify the nature of the accreting objects, I have carried out a detailed study of radio variability along with a multi-wavelength (optical and X-ray) examination of compact objects in some of these GCs. In this talk, I will discuss the presence of a mixed population of compact objects in these clusters with at least a few new BH candidates in them. These investigations allow the first statistical determination of the presence of accreting BHs in GCs and improve our understanding of unusual NSs and WD binaries. Furthermore, I will touch upon future radio and multi-wavelength campaigns planned with the aim of establishing the true nature of compact objects from their radio behaviour alone. I will end the talk with a discussion on whether a substantial population of compact objects in GCs, including radio quite thermonuclear supernovae, are potential sources of fast radio bursts (FRBs) - a study I initiated to investigate the origin of FRBs in GCs.